The present invention relates to a guide apparatus having a dustproof structure (hereinlater, which may be called "dustproof guide apparatus") for guiding a movable table or the like, and more particularly, to a dustproof guide apparatus provided with an outer (armor) cover.
FIG. 10 shows one example of a conventionally known dustproof guide apparatus utilizing a ball screw. The dustproof guide apparatus shown in FIG. 10 comprises a screw shaft 1 supported only to be rotatable, a nut member 2 screwed to the screw shaft 1 and an outer cover 3 covering the screw shaft 1 and the nut member 2. The outer cover 3 is formed with an upper opening 4, in an illustrated state, in parallel to the screw shaft 1. The nut member 2 is integrally formed with a movable member 5, which is secured to a member to be guided, in a manner such that the movable member 5 is moved linearly along the opening in accordance with the rotation of the screw shaft 1. The opening 4 of the outer cover 3 is covered by a seal member 6 made of rubber, and the seal member 6 is formed with one linear cut (cut line) 6a along the screw shaft 1. The movable member 5 forcibly bents outward the seal member 6 along the cut line 6a so as to project outward through an opening O formed by forcibly bending the seal member 6. The movable member 6 carries out a linear reciprocal motion along the cut line 6a while widening both sides of the cut line 6a of the seal member 6. According to this structure, dust or the like generated from the ball screw can be prevented from being discharged outward by covering the screw shaft 1 and the nut member 2 by the outer cover 3 and the seal member 6.
However, in the structure of the dustproof guide apparatus shown in FIG. 1 in which the linear cut 6a is formed to the seal member 6, a gap having a slight width will appear between portions 6b and 6c of the seal member 6 facing each other along the cut line 6a, and the width of this gap will be gradually widened while the movable member 5 being reciprocally moved repeatedly, which provides a problem such that dust or the like is discharged through such widened gap outward the outer cover 3. Thus, according to the structure of the conventional dustproof guide apparatus such as shown in FIG. 10, it is difficult to achieve high dustproof property.